Analysis: Undocumented Immigrants Not Linked With Higher Crime Rates

Decades of research largely dismiss the commonly-held belief that immigrants are disproportionately responsible for committing crimes. Numerous studies, in fact, suggest immigrants may play a role in slightly suppressing crime rates. Still, many Americans continue to associate immigration with out-of-control crime, perceiving the presence of foreigners as a public safety threat. Academic research examining immigration and crime has relied largely on foreign-born population totals as estimates for only undocumented immigrants are scarcely available. This has made distinguishing any effects of undocumented immigrants from the majority of those legally in the country difficult, leading some to maintain that the undocumented may yet pose significant public safety risks.

Governing conducted an analysis to identify how this demographic, the subject of much of the current federal policy debate, may be associated with crime rates. We utilized recently published estimates from the Pew Research Center for “unauthorized immigrants,” a group that includes individuals crossing the border illegally or overstaying visas. Regression models compared these estimates to crime rates in 154 metro areas, controlling for several socioeconomic measures. Our analysis found a statistically significant correlation for unauthorized immigrant populations with slightly lower violent and property crimes rates, while no relationship was present for murder rates.

Methodology

Our sample consisted of all metropolitan statistical areas with available crime and unauthorized immigrant data. The Pew Research Center published 2014 unauthorized immigrant estimates for 155 metro areas, expressed as a share of an area's total population. Pew computed its estimates by subtracting estimated numbers of lawful immigrant admissions from survey estimates of the total foreign born population. For crime rates, 2013-2015 three-year average rates were computed for metro area violent crimes, property crimes and murders using data reported by the FBI’s Uniform Crime Reporting (UCR) program. Using three-year averages better reflects crime in individual regions than one-year data as some rates fluctuate significantly from year to year. Aggravated assaults account for the majority of violent crimes in most regions, while property crimes are mostly larcenies or thefts. While the FBI did not publish data for all three years for some metro areas, only the Cleveland, Ohio, metro area was missing data for all three years, so it was excluded from the analysis.

A multiple linear regression analysis was then performed using data from the remaining 154 metro areas. Three separate models were run comparing unauthorized immigration with violent crime rates, property crime rates and murder rates. The following control variables were utilized in the models: Men ages 15 to 34, black population, density, institutionalized population, manufacturing industry, median home value, female family households with no husbands, retail/hospitality industry, households without access to vehicles, rental households and the unemployment rate. (See variable descriptions.) Several excluded measures mirroring these control variables were also tested, but did not have a major effect on the results and were not found to be statistically significant in the regression models. They include education levels, employment-to-population ratios, home vacancy rates, median incomes, poverty rates and total populations. According to the FBI, other factors known to influence crime rates include an area's climate, citizens' crime reporting practices and the strength of law enforcement agencies.

Results

Violent Crime: In the violent crimes model, shares of unauthorized immigrants had a statistically significant relationship with slightly lower crime rates, with a p-value of .042. These crimes include murders, rapes, robberies and aggravated assaults. Among the control variables, the black population, rental households and population density were also found to be statistically significant positive predictors of violent crime rates. Results suggested a statistically significant negative relationship for median home values and lack of access to vehicles.

Property Crime: Unauthorized immigrant populations were also correlated with lower property crime rates, with a p-value of .001. This category includes burglaries, larceny/thefts and motor vehicle thefts. For every one percentage-point increase in the unauthorized immigrant share of the population, average property crime rates dropped by 94 incidents per 100,000 residents. The median home value and lack of access to vehicles control variables were similarly shown to have a negative relationship. Rentals and mother-headed households without husbands were positively correlated with property crime rates. The manufacturing industry, institutionalized population and young men variables were also correlated, but only at the p ≤ .1 level.

Murder: For murder rates, no association with unauthorized immigrant populations was found. While not statistically significant, the sign of the regression coefficient was negative, suggesting that it’s highly unlikely that unauthorized immigrants contribute to higher murder rates. The black population, unemployment rates, rental households and mother-headed households without husbands were positively correlated with murder rates in the model. This model explained 51 percent of the variation in crime rates, the most of the three models.

Summary Statistics

The following table summarizes statistics for the 15 variables used to characterize the 154 metro areas reviewed. (See variable descriptions.)

Metro area measures

Mean

Standard Deviation

Violent Crime Rate Average

403.9

154.9

Property Crime Rate Average

2846.5

736.2

Murder Rate Average

4.7

2.5

Age 15-34 Men %

14.3

2.1

Black Population % (Square root)

3.0

1.4

Density (Ln)

8.0

0.6

Institutionalized Population % (Square root)

1.1

0.3

Manufacturing Industry %

9.8

4.3

Median Home Value (Ln)

12.1

0.4

Mother Households Without Husband %

13.2

2.6

No Vehicle Households % (Ln)

2.0

0.3

Rentals % (Ln)

3.6

0.2

Retail/Hospitality Industry %

21.9

3.6

Unauthorized Immigrant Population %

3.6

2.4

Unemployment Rate

6.6

2.7

Regression Results

Property Crimes

Violent Crimes

Murders

b

Std. Error

b

Std. Error

b

Std. Error

Immigration

Unauthorized Immigrant Population

-93.658***

(28.284)

-12.394*

(6.038)

-0.1

(0.084)

Demographics

Age 15-34 Men

-60.016

(36.209)

-15.212

(7.729)

-0.252*

(0.107)

Black Population (Square root)

27.003

(43.957)

39.423***

(9.383)

1.085***

(0.13)

Mother Households Without Husband

85.079**

(29.682)

11.098

(6.336)

0.228**

(0.088)

Housing

Density (Ln)

-102.26

(149.828)

72.634*

(31.983)

0.642

(0.443)

Median Home Value (Ln)

-449.787*

(191.769)

-99.73*

(40.936)

-0.833

(0.566)

Rentals (Ln)

2216.549***

(578.245)

367.339**

(123.436)

3.721*

(1.708)

Law Enforcement

Institutionalized Population (Square root)

-301.876

(166.02)

31.011

(35.44)

-0.464

(0.49)

Employment

Retail/Hospitality Industry

3.12

(17.536)

3.001

(3.743)

-0.022

(0.052)

Manufacturing Industry

-26.383

(14.322)

-2.686

(3.057)

-0.027

(0.042)

Unemployment Rate

0.296

(24.132)

3.488

(5.151)

0.158*

(0.071)

Transportation

No Vehicle Households (Ln)

-734.831**

(241.591)

-155.336**

(51.571)

-1.892**

(0.714)

R²

0.35

0.33

0.51

N

154

154

154

*p ≤ 0.05; **p ≤ 0.01; ***p ≤ .001.

Separately, without controlling for other measures, areas where unauthorized immigrants were most prevalent generally reported lower crime rates than other regions. The 20 metro areas where unauthorized immigrants account for the highest shares of the total population recorded, on average, property crime rates 10 percent lower and violent crime rates 8 percent lower than those of all other regions.

Related Research

Our results mirror academic research more broadly examining crime and immigration. Typically, these studies have compared changes in the foreign born population with crime rates. The vast majority purport either no association between immigration and crime, or suggest immigrant populations are correlated with lower crime rates. A recent study published in the Journal of Ethnicity in Criminal Justice examined changes in crime across metro areas over a 40-year period, finding immigration to be associated with declines in both violent and property crimes. At the individual level, a 2014 Justice Quarterly paper concluded immigrants were no more prone to commit crimes than natives. Studies examining incarceration rates have further reached similar conclusions, such as a 2007 paper published by the National Bureau of Economic Research and a more recent analysis from the American Immigration Council.

Data Limitations

This analysis was limited to a sample of 154 metro areas with available data. It should also be noted that findings reflect only a one-year snapshot (2014) of the unauthorized immigrant population. Pew has not published estimates of unauthorized immigrants for prior years at the metro-area level, so conducting a longitudinal analysis was not possible. Additionally, some of Pew’s estimates are subject to large margins of error, particularly for smaller regions.

Variable Descriptions

Average Violent Crime Rate: Reported murders, rapes, robberies and aggravated assaults per 100,000 residents, calculated as an annual average for 2013-2015. The FBI did not report annual rates for some agencies for all three years. (Source: FBI Uniform Crime Reporting program, Table 6)

Average Property Crime Rate: Total reported burglaries, larceny/thefts and motor vehicle thefts per 100,000 residents within a metro area. An annual average rate was computed for 2013-2015. The FBI did not report annual rates for some agencies for all three years. (Source: FBI Uniform Crime Reporting program, Table 6)

Average Murder Rate: Total reported murder and nonnegligent manslaughter incidents per 100,000 residents within a metro area, computed as a three-year annual average for 2013-2015. The FBI did not report annual rates for some agencies for all three years. (Source: FBI Uniform Crime Reporting program, Table 6)

Unauthorized Immigrant Population: Immigrants who are not assumed to be lawful immigrants, expressed as a share of a metro area’s 2014 total population. Pew Research Center computed unauthorized immigrant estimates by subtracting known legal immigrant population figures from Census survey estimates of the total foreign born population. (Source: Pew Research Center)

Age 15-34 Men: The estimated share of a metro area’s total population for males between the ages of 15 and 34. This demographic is known to commit crimes at notably higher rates. (Source: 2010-2014 Census American Community Survey data)

Black Population: The African American share of a metro area’s total population. The square root of values is used to account for the skewed distribution. (Source: 2010-2014 Census American Community Survey data)

Density: A metro area’s population density. Natural logs of values are used to account for the skewed distribution. (Source: 2010 U.S. Census Bureau data)

Institutionalized Population: The Census Bureau defines the institutionalized population as those “primarily ineligible, unable, or unlikely to participate in the labor force while residents of institutional group quarters.” Individuals incarcerated in correctional facilities account for the vast majority of this group. The measure, defined as a percentage of the total population, serves as a proxy for police enforcement. The square root of values is used to account for the skewed distribution. (Source: 2010 Census estimates)

Manufacturing Industry: The manufacturing industry share of an area’s total employment. (Source: 2010-2014 Census American Community Survey data)

Median Home Value: The median value of owner-occupied housing units within a metro area. Natural logs of values are used to account for the skewed distribution. (Source: 2010-2014 Census American Community Survey data)

Mother Households Without Husband: The percentage of all households that are families headed by females without a husband present. (Source: 2010-2014 Census American Community Survey data)

Retail/Hospitality Industry: This measures considers workers employed in the following industries: retail trade, arts, entertainment, and recreation, and accommodation and food services. Values are expressed as share of a metro area’s total employment. Areas with larger values tend to be tourist or retirement destinations with warmer climates. (Source: 2010-2014 Census American Community Survey data)

Rentals: The share of all occupied housing units that rentals account for. Natural logs of values are used. (Source: 2010-2014 Census American Community Survey data)

No Vehicle Households: The share of all occupied housing units without access to motor vehicles. The FBI reports that modes of transportation are among factors known to contribute to crime rates. In addition, regions with fewer vehicles can be expected to have lower property crime rates as these crimes are often related to vehicle break-ins or motor vehicle thefts. Natural logs of values are used to account for the skewed distribution. (Source: 2010-2014 Census American Community Survey data)

SOURCE: Crime rates are 2013-2015 annual average rates per 100,000 residents calculated from the FBI'sUniform Crime Reporting data. Unauthorized immigrant totals were published by the Pew Research Center and represent estimates for 2014.